PHPCS throws errors determining auto report width when shell_exec is disabled

[linux4me]

If a server has shell_exec() disabled for security reasons, the error logs fill up with warnings like this each time a PHP CodeSniffer command is run:
PHP Warning: shell_exec() has been disabled for security reasons in /.composer/vendor/squizlabs/php_codesniffer/src/Config.php on line 222
Disabling shell_exec() doesn't interfere with PHP CodeSniffer's functioning, but a simple check to see if shell_exec() is disabled with function_exists() would prevent the warning on servers that disable shell_exec().